Novel automatic locking device for safety belts

ABSTRACT

An automatic locking device for a safety belt for retaining a person in a vehicle comprising a rotor shaft rotatable in a casing for reeling up the belt and a rotor rotatable together with the shaft and means to lock the rotor to the casing in response to centripetal forces produced by withdrawal of the belt. The device includes a two-armed locking member mounted on a horizontal shaft carried by a cover plate substantially transversally to the shaft of the rotor and adapted on acceleration or deceleration forces exceeding a predetermined value actuate a swingable element which is suspended pivotably relatively to said cover plate to take a position releasing the means locking the rotor relative the casing. By mounting the swingable element at an upper point freely pivotable on the cover plate and forming it on both sides of one arm of the two-armed locking member with cam surfaces, the force necessary for actuating the swingable element is reduced and the weight of the locking device is a reduced weight and its reactivity and reliability is improved. In addition the two-armed locking member can be mounted on a shaft extending in other than the horizontal direction.

United States Patent Rex 54] NOVEL AUTOMATIC LOCKING DEVICE FOR SAFETYBELTS [72] Inventor: Gert Ingmar Rex, Hamstad, Sweden [73) Assignee: ABAutoindustri, Halmstad, Sweden [22] Filed: Oct. 21,1971

[21] Appl. No.: l9l,l7l

14 1 Oct. 24, 1972 Primary Examiner-James T. McCall Attorney-B. E.Shlesinger et al.

[57] ABSTRACT An automatic locking device for a safety belt forretaining a person in a vehicle comprising a rotor shaft rotatable in acasing for reeling up the belt and a rotor rotatable together with theshaft and means to lock the rotor to the casing in response tocentripetal forces produced by withdrawal of the belt. The deviceincludes a two-armed locking member mounted on a horizontal shaftcarried by a cover plate substantially transversally to the shaft of therotor and adapted on acceleration or deceleration forces exceeding apredetermined value actuate a swingable element which is suspendedpivotably relatively to said cover plate to take a position releasingthe means locking the rotor relative the casing. By mounting theswingable element at an upper point freely pivotable on the cover plateand formingit on both sides of one arm of the two-armed locking memberwith cam surfaces, the force necessary for actuating the swingableelement is reduced and the weight of the locking device is a reducedweight and its reactivity and reliability is improved. In addition thetwo-armed locking member can be mounted on a shaft extending in otherthan the horizontal direction.

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NOVEL AUTOMATIC LOCKING DEVICE FOR SAFETY BELTS FIELD OF THE INVENTIONbeing adapted to cooperate with one or several locking pawl teeth in thecasing and a two-armed locking member which is mounted in a bearing on ahorizontal shaft carried by a cover plate substantially transversally tothe shaft of the rotor, said locking member having a first arm and asecond arm, which second arm cooperates with a swingable elementsuspended pivotably relatively to said cover plate and adapted onoccurrance of acceleration or deceleration forces exceeding apredetermined value to swing the second arm so as to cause the first armto be swung into a releasing position actuating the locking pawl, inwhich position the locking pawl engages a pawl locking tooth for lockingthe rotor relative the casing, cam surfaces being formed on a swingingmovement of the swingable element in a plane substantially parallel tothat of the cover plate to bring about said swinging movement of thearms.

THE PRIOR ART In an automatic locking device of this type which isdescribed in detail e.g. in the US. Pat. No. 3,593,942 the swingableelement is suspended from a pivot rigidly secured to the casing and thecam surfaces are provided on e. g. the casing or the cover plate,respectively, in order to lift the swingable element when it is swingingin a plane substantially parallel to that of the cover plate away fromsaid cover plate so that the swingable element becomes capable ofcausing the swinging movement of the arms of the locking member and tobring about the locking effect. It has now become evident that this typeof locking device in spite of the essential improvement attained overearlier known types still has two major drawbacks which are: firstly theautomatic locking device must be installed in the vehicle in exactposition relative the vertical line to ensure that the swingable elementin non-actuated state shall be suspended correctly which means that thefixed pivot of the swingable element must be positioned in a verticalplane through the rotor shaft and secondly the lifting of the elementout of the cover plate when said member is swinging in parallelrelationship to the cover plate involves that a relatively great forceis consumed for the lifting operation proper for which reason the angleof swinging movement can be reduced so much that the required lockingeffect can not be obtained at a pre-determined desired G-value.

OBJECTS OF THE INVENTION One main object of the invention is thus toprovide a device which allows that the automatic locking device can beinstalled in any position relative the vertical line without any otherchange being required to be effected but a turning of the cover plateproper and to provide such a structure of the swingable element that noenergy will be consumed for lifting the element proper during theswinging movement whereby the improved device reacts more rapidly andfurthermore the swingable element can be reduced in weight.

SUMMARY OF THE INVENTION This object is fully realized according to theinvention substantially thereby that the swingable element is mountedfreely pivotable at an upper point on the cover plate and on both sidesof said second arm formed with the cam surfaces.

THE DRAWINGS Further objects and advantages will become apparent fromthe following description, considered in connection with theaccompanying drawings which form part of this specification and whichillustrate by way of example a known automatic locking deviceincorporating the improved structure according to the invention.

Of the drawings,

FIG. I is a side view of the automatic locking device with one sidecover removed;

FIG. 2 is a sectional view following the line ll-II of FIG. 1;

FIG. 3 is a side view taken from the opposite side of the automaticlocking device with the other side cover removed;

FIG, 4 is a view of the automatic locking device viewed from the sameside as in FIG. 1 but with the swingable mechanism removed;

FIG. 5 is a front view of a cover plate formed according to theinvention;

FIG. 6 is a representation of the cover plate viewed from one side;

FIG. 7 is a front view of the swingable element formed according to theinvention;

FIG. 8 is a sectional view following the line VIII- VIII of FIG. 7;

FIG. 9 is a sectional view following the line IX-IX of FIG. 7; and

FIG. 10 is a partly sectional view of an embodiment of the cover platewhen the locking device is mounted inclined relatively to the verticalline.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to theillustrated embodiment of the automatic locking device having a coverplate and a swingable element according to the invention, referencenumeral 1 denotes a U-shaped casing for an automatic locking devicegenerally denoted 2 for a safety belt 3. The safety belt 3 consists of astrap which in known manner by means of a coil spring 4 is wound up on ashaft 5. The ends of the shaft 5 are mounted in bushings 6, which arerotatably mounted in recesses in the casing 1. In spaced relation to,and parallel with, the shaft 5 the bushings 6 in addition support a rod7 which between the discs forms an interior attachment for the inner endof the strap 3 and outside of the one bushing 6 the interior attachmentfor the spring 4. The

coil spring 4 is encased in a lateral cover plate 8, which is attachedonto the casing l. The outer end of the spring 4 is connected to anattachment means 9, which here is constituted by an aperture in thelateral cover plate 8.

Fixed on that end portion of the shaft 5 which is located remote fromthe end carrying the spring and which projects beyond the left handbushing 6 in FIG. 2 and thus beyond the casing 1, is a suitablycircular, disc-shaped locking means casing or rotor 10. In theembodiment shown, this rotor 10 is formed with a wedge-shaped recess 11within which a locking pawl 12 is mounted pivotably. Of course, it ispossible to provide any desired number of recesses and locking pawlsabout the circumference of the rotor 10, but for case of simplicity,only one such device is shown here. As will be seen from FIG. 4, the topof the wedge-shaped recess 11 is directed approximately towards thecenter of the rotor 10.

As will be understood best from FIG. 4, which shows the automaticlocking device in locked position with the locking pawl 12 engaging alocking tooth 13 of a ratchet member 14, surrounding the rotor 10, whichis in rigid connection with the casing 1, the locking surface 15 on eachlocking tooth extends in the embodiment shown in the radial direction ofthe rotor, the recess 11 having an also radially extending contactsurface 16 for the locking pawl 12. The rotor 10 is formed with acentral cylindric portion 19 which constitutes a guide or journal for aninertia-responsive disc 21 the function of which is explained in moredetail in the above-mentioned U.S. Pat. No. 3,593,942.

In the embodiment shown, the inertia-responsive disc 21 is freelypivotable about the cylindrical journal 19. To prevent the disc 21 fromaxially sliding off from the central journal 19 there is provided awasher 22 which rests on a shoulder of the central journal and whichallows the disc 21 to rotate about the central journal 19. A plate 23covering the rotor 10 and the inertia disc 21 and having an opening 24(FIG. 5) is fixed onto the ratchet member 14. The opening 24 leavesspace for a locking member 25 formed as a two-armed lever, the pivotaxis 26 of which is fitted in the central portion of the lever, and inthe operative position of the locking device extends substantiallyhorizontally, and is mounted between two cars 27 located in spacedrelation from one another and projecting from the central portion of thecover plate 23. The upper arm of the locking member 25 is preferablyheavier and/or longer than the lower arm thereof and located so muchoutside the rotating shaft 26 that it is normally retained in thecounterclockwise inclined position shown in FIG. 2. The upper arm of thelocking member 25 is provided with a resilient locking hook 28 devisedwhen in clockwise inwardly turned position resiliently to engage lockingteeth 29 which project radially on the outer surface remote from therotor 10 of the disc 21.

Formed in the surface of the rotor 10 facing the disc 21 is an arcuategroove 39 (FIG. 4) into which a pressure spring 40 has been inserted.Bearing against the one end of the spring 40 is a pin 41, projectingfrom the inertia-responsive disc 21, into the groove 39 within which thepin 41 on a relative turning movement between the rotor 10 and the disc21 is freely movable against the action of the spring 40.

If the rotor 10 is accelerated very rapidly, which occurs, for example,when a person secured in the belt is thrown forwards due to a collision,a locking of the rotor is brought about immediately, as is described indetail in the US. Pat. No. 3,593,942 referred to hereinbefore. Theinertia-responsive disc 21 which normally is carried along with therotor 10 against the action of the pressure force from the spring 40will, due to the inertia forces which act on the same, not be capable ofaccelerating as rapidly as the rotor 10, and as a consequence thelocking pawl 12 will move more rapidly than the disc 21 and be swunginto the radial position which is shown in FIG. 4 where the locking pawl12 is in engagement with a locking tooth 13.

The critical acceleration on which the locking pawl is released isdefined by the force acting on the disc i.e. in the embodiment shown,the spring tension of the spring 40 and means may be provided to adjustsaid spring force and therewith the critical acceleration.

The above-described locking on rapid acceleration is effected as aconsequence of too a rapid withdrawal of the belt entirely independentlyof the locking member 25. This locking member has for its object tobring about a locking of the disc 21 in those cases where greataccelerations which act on a person secured in the belt may not resultin a corresponding acceleration of the belt 3 and the rotor 10, whichsituation can be imagined to be brought about when the vehicle isimpacted laterally, and furthermore the locking member 25 constitutes anadditional security means on great accelerations even in such caseswhere the disc 21 will become operative.

The novel feature of the invention resides in the improved swingableelement and the attachment of the cover disc on the side plate of therotor. Formed by punching on the upper portion of the cover plate 23 isan outwardly bent pin 30 from which a swingable element 31 is suspendedfor free pivotable movement in both axial and the radial directions ofthe rotor 10. The swingable element 31 which constitutes an additionallocking element has a plane extending substantially transversally to theaxis of the shaft 5 and has at its top a bent end portion 46 (FIG. 9)which is formed with an aperture 47 in which the pin 30 is positioned.The swingable element 31 has a central opening 32 for the locking member25, said opening 32 having a lower element portion 33 located betweenthe cover plate 23 and the lower arm 34 of the locking member 25. Thislower portion 33 of the element 31 is bent out from the main plane ofthe generally disc-shaped element towards the cover plate 23 as isevident most clearly from the FIG. 8 and forms a central sliding surface42 which is defined by cam surfaces 35, 36 directed upwards anddownwards, respectively.

The cover plate 23, which in detail is illustrated in the FIGS. 5 and 6,is substantially circular and formed with a recess 38 and grooves 50 forscrews. The sliding surface 42 of the swingable element 31 abuts againstthe edge 45 of the cover plate 23, and as the breadth of the abuttingsurface can be made little in the radial direction, the friction forcesbreaking the swinging movement of the swingable element 31 become verysmall. It is possible to make the sliding surface 42 of said elementvery narrow and cause it to slide against a cover plate 23 having norecess 38 and further it is possible, if desired, to cause the slidingsurface 42 to bear against any other arbitrary, fixed portion of theside plate of the rotor.

To mount the cover plate 23 on the side plate of the rotor holes 52(FIG. 4) are formed in positions corresponding to the desired finalinclination of the automatic locking device and thereafter the coverplate 23 is fixed by driving home screws 51 (FIG. 1), whereupon a fineadjustment of the cover plate 23 is rendered possible by the grooves 50so that the pin 30 can be brought into a position substantially inalignment with the central line of the shaft 5 whereby the swingablemember 31 is caused to take a predetermined centered position relativethe locking member 25 mounted swingably on the cover plate 23. In casethe final mounting of the automatic locking device in a vehicle can bedetermined beforehand within exactitude of one or several degrees of thecircle, the grooves 50 may be replaced by circular holes fitting to thedimensions of the screws.

OPERATION OF THE PREFERRED EMBODIMENT The described mechanism with theimproved cover plate and swingable element becomes operative in thefollowing manner. On a strong deceleration or acceleration of thevehicle in the direction of movement of the vehicle, the element 31 willbe swung in the plane of the cover plate 23 provided that said plate ispositioned in the direction of movement. Hereunder, the element 31 willslide or freely swing in said plane so that the lower arm 34 of thelocking member, which bears against or is positioned immediatelyadjacent the outwards facing surface of the lower element portion 33, toslide upwardly on that of the cam surfaces 35 or 36, respectively, ofthe element which is moving towards the arm 34, and thereby the arm 34will be swung outwards and the locking hook 28 of the locking deviceestablish engagement with one tooth on the disc 21 whereby the rotor islocked. In this swinging movement of the arms of the locking member, theelement 31 will be actuated only by the small friction forces acting onits sliding surface 42 and of the insignificant force required to effectthe swinging or pivoting movement of the light-weight locking member,and, consequently, the swinging movement of the element 31 will not bedisturbed to a noteworth degree, whereby it is ensured that a fullextent swinging movement of the locking member is obtained. As onlynegligeably small forces disturbing said movement act on the swingableelement 31, this element can be made very light and highly sensitive. Inthose cases where the vehicle is exposed to forces which force theswingable element 31 outwards from the cover plate 23, the lower portion33 of said element will force the arm 34 in outward direction and bringabout the required locking effect.

FIG. illustrates an embodiment of the cover plate 23 intended to be usedin that case when the automatic locking device can not be mounted withthe rotor shaft 5 extending horizontally. It is obvious that thepivotable member must be suspended vertically and the invention renderspossible by use of the specific cover plate to allow by a simplecorrection an inclined mounting of the locking device. When employingthe embodiment shown in FIG. 10, the locking device is intended to bemounted in the vehicle so that the ratchet member 14 is inclined by anangle relatively to the vertical plane. in order to render possiblevertical suspension of the swingable element the central portion of thecover plate 23 which carries the pin 30 and the ears 27, has been bentout with the same angle from the peripheral portions of the cover platebearing against said ratchet member so that upon installation of thelocking device the pin 30 and the ears 27 will be positioned in the samevertical plane.

It will be understood from the description that the invention hasprovided a device which can be mounted in any desired position relativethe casing of the automatic locking device, which permits divergation ofthe rotor shaft from the horizontal plane, and which responds veryrapidly and in a reliable manner on occurring accelerations anddecelerations.

While several more or less specific embodiments of the invention havebeen shown and described, it is to be understood that this is forpurpose of illustration only, and that the invention is not to belimited thereby, but its scope is to be determined by the appendedclaims.

lclaim:

1. In an automatic locking device for a safety belt for retaining aperson in a vehicle, comprising a rotor shaft (5) mounted rotatablywithin a casing for reeling up the belt and a rotor (10) rotatabletogether with the shaft, on the circumference of which rotor at leastone locking pawl (12) is disposed movable outwardly in response tocentripetal forces coming into existence when the belt is withdrawn,said locking pawl being adapted to cooperate with one or several lockingpawl teeth (13) in the casing and a two-armed locking member (25)mounted on a horizontal shaft (21) carried by a cover plate (23)substantially transversally to the shaft (5) of the rotor, said lockingmember having a first arm and a second arm (34) which second armcooperates with a swingable element (31) suspended pivotably relativelyto said cover plate and adapted on acceleration or deceleration forcesexceeding a predetermined value to swing the second arm (34) so as tocause the first arm to be swung into a releasing position actuating thelocking pawl, in which position said locking pawl engages a pawl lockingtooth for locking the rotor relative the casing, cam surfaces (35, 36)being formed on the swingable element in a plane substantially parallelto that of the cover plate to bring about said swinging movement of thearms, the characterizing feature that the swingable element (31) at anupper point (30) is mounted freely pivotable on said cover plate (23)and on both sides of said second arm (34) formed with the cam surfaces(35, 36).

2. In the device as claimed in claim 1, the further characterizingfeature that the swingable element (31) is suspended from an outwardsbent pin (30) formed by punching from the cover plate (23) made of sheetplate material.

3. In the device as claimed in claim 1, the further characterizingfeature that the swingable element (31) is disc-shaped and has a centralopening (32) for the locking member (25) and that a portion (33) of theswingable element located between the second arm (34) and said coverplate (23) is bent towards said cover plate to form a sliding surface(42) bearing against a fixed surface and the two cam surfaces (35, 36)defining said sliding surface (42).

1. In an automatic locking device for a safety belt for retaining aperson in a vehicle, comprising a rotor shaft (5) mounted rotatablywithin a casing for reeling up the belt and a rotor (10) rotatabletogether with the shaft, on the circumference of which rotor at leastone locking pawl (12) is disposed movable outwardly in response tocentripetal forces coming into existence when the belt is withdrawn,said locking pawl being adapted to cooperate with one or several lockingpawl teeth (13) in the casing and a two-armed locking member (25)mounted on a horizontal shaft (21) carried by a cover plate (23)substantially transversally to the shaft (5) of the rotor, said lockingmember having a first arm and a second arm (34) which second armcooperates with a swingable element (31) suspended pivotably relativelyto said cover plate and adapted on acceleration or deceleration forcesexceeding a predetermined value to swing the second arm (34) so as tocause the first arm to be swung into a releasing position actuating thelocking pawl, in which position said locking pawl engages a pawl lockingtooth for locking the rotor relative the casing, cam surfaces (35, 36)being formEd on the swingable element in a plane substantially parallelto that of the cover plate to bring about said swinging movement of thearms, the characterizing feature that the swingable element (31) at anupper point (30) is mounted freely pivotable on said cover plate (23)and on both sides of said second arm (34) formed with the cam surfaces(35, 36).
 2. In the device as claimed in claim 1, the furthercharacterizing feature that the swingable element (31) is suspended froman outwards bent pin (30) formed by punching from the cover plate (23)made of sheet plate material.
 3. In the device as claimed in claim 1,the further characterizing feature that the swingable element (31) isdisc-shaped and has a central opening (32) for the locking member (25)and that a portion (33) of the swingable element located between thesecond arm (34) and said cover plate (23) is bent towards said coverplate to form a sliding surface (42) bearing against a fixed surface andthe two cam surfaces (35, 36) defining said sliding surface (42).